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1.
Ecotoxicol Environ Saf ; 203: 110999, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888604

RESUMO

Aluminium (Al) is a key element that plays a major role in inhibiting plant growth and productivity under acidic soils. While lipids may be involved in plant tolerance/sensitivity to Al, the role of monogalactosyldiacylglycerol (MGDG) in Al response remains unknown. In this study, Arabidopsis MGDG synthase (AtMGD) mutants (mgd1, mgd2 and mgd3) and wild-type (Col-0) plants were treated with AlCl3; the effect of aluminium on root growth, aluminium distribution, plasma membrane integrity, lipid peroxidation, hydrogen peroxide content and membrane lipid compositions were analysed. Under Al stress, mgd mutants exhibited a more severe root growth inhibition, plasma membrane integrity damage and lipid peroxidation compared to Col-0. Al accumulation in root tips showed no difference between Col-0 and mutants under Al stress. Lipid analysis demonstrated that under Al treatment the MGDG content in all plants and MGDG/DGDG (digalactosyldiacylglycerol) remarkably reduced, especially in mutants impairing the stability and permeability of the plasma membrane. These results indicate that the Arabidopsis mgd mutants are hypersensitive to Al stress due to the reduction in MGDG content, and this is of great significance in the discovery of effective measures for plants to inhibit aluminium toxicity.


Assuntos
Alumínio/toxicidade , Arabidopsis/efeitos dos fármacos , Galactolipídeos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Poluentes do Solo/toxicidade , Alumínio/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Galactolipídeos/genética , Galactosiltransferases/genética , Galactosiltransferases/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Lipídeos de Membrana/metabolismo , Mutação , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Poluentes do Solo/metabolismo
2.
Ecotoxicol Environ Saf ; 204: 111056, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32763566

RESUMO

Strontium (Sr) is an emerging environmental pollutant that has become a major global concern after the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in 2011. Although many studies have demonstrated the harmful effects of Sr on plant growth and development at the physiological level, knowledge regarding how plants sense and respond to Sr stress at the molecular level is limited. Recent studies have suggested that microRNAs (miRNAs) function as key regulators of plant growth and development as well as in the responses of plants to environmental stresses, including salinity, drought, cold, nutrient starvation, and heavy metals. In this study, we examined the global expression profile of miRNAs under Sr stress using small RNA sequencing analysis in Arabidopsis to better understand the molecular basis of plant responses to Sr stress. To identify specific Sr-responsive miRNAs, we performed comparative miRNA expression profiling analysis using control, CaCl2-, and SrCl2-treated seedlings. Compared to the control treatment, the expressions of most miRNAs were considerably decreased in the Sr-treated seedlings. However, under Sr stress, the expressions of primary miRNAs (pri-miRNAs) and their target genes were significantly increased; the protein levels of HYPONASTIC LEAVES 1 (HYL1), one of the core components of the microprocessor complex, were strongly reduced despite the increased HYL1 mRNA expression. In addition, hyl1-2 mutant plants were shown to be more sensitive to Sr stress than wild-type plants. Collectively, our results strongly suggested that Sr stress may be associated with the disruption of miRNA biogenesis by reducing the protein level of HYL1, which is required to maintain proper growth and development for plants. Our findings further indicated that some miRNAs may play important roles in plant responses to Sr stress.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/efeitos dos fármacos , MicroRNAs/biossíntese , Estresse Oxidativo/efeitos dos fármacos , Proteínas de Ligação a RNA/metabolismo , Poluentes do Solo/toxicidade , Estrôncio/toxicidade , Arabidopsis/genética , Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , MicroRNAs/genética , Estresse Oxidativo/genética , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Processamento Pós-Transcricional do RNA
3.
Nat Commun ; 11(1): 4284, 2020 08 27.
Artigo em Inglês | MEDLINE | ID: mdl-32855409

RESUMO

Cytokinins are mobile multifunctional plant hormones with roles in development and stress resilience. Although their Histidine Kinase receptors are substantially localised to the endoplasmic reticulum, cellular sites of cytokinin perception and importance of spatially heterogeneous cytokinin distribution continue to be debated. Here we show that cytokinin perception by plasma membrane receptors is an effective additional path for cytokinin response. Readout from a Two Component Signalling cytokinin-specific reporter (TCSn::GFP) closely matches intracellular cytokinin content in roots, yet we also find cytokinins in extracellular fluid, potentially enabling action at the cell surface. Cytokinins covalently linked to beads that could not pass the plasma membrane increased expression of both TCSn::GFP and Cytokinin Response Factors. Super-resolution microscopy of GFP-labelled receptors and diminished TCSn::GFP response to immobilised cytokinins in cytokinin receptor mutants, further indicate that receptors can function at the cell surface. We argue that dual intracellular and surface locations may augment flexibility of cytokinin responses.


Assuntos
Arabidopsis/metabolismo , Citocininas/metabolismo , Proteínas Recombinantes/metabolismo , Adenina/análogos & derivados , Adenina/farmacologia , Arabidopsis/citologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Líquido Extracelular/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Histidina Quinase/genética , Histidina Quinase/metabolismo , Mutação , Plantas Geneticamente Modificadas , Proteínas Recombinantes/genética , Transdução de Sinais
4.
Artigo em Inglês | MEDLINE | ID: mdl-32502716

RESUMO

Thymol is a natural phenolic monoterpene widely produced by different species belonging to the Labiateae family. Although the thymol phytotoxicity is well known, the knowledge of its potential toxic mechanism is still limited. In this regard, the model species Arabidopsis thaliana was treated for 16 days by sub-irrigation with 300 µM of thymol. The results confirmed the high phytotoxic potential of this phenolic compound, which caused a reduction in plant growth and development. Thymol induced a water status alteration accompanied by an increase in ABA content and stomatal closure. Furthermore, leaves appeared necrotic in the margins and their temperature rinsed. The increase in H2O2 content suggested an oxidative stress experienced by treated plants. Both metabolomic and proteomic analysis confirmed this hypothesis showing a strong increase in osmoprotectants content, such as galactinol and proline, and a significant up-accumulation of proteins involved in ROS detoxification. Furthermore, the down-accumulation of proteins and pigments involved in the photosynthetic machinery, the increase in light sensitivity and the lower PSII efficiency well indicated a reduction in photosynthetic activity. Overall, we can postulate that thymol-induced phytotoxicity could be related to a combined osmotic and oxidative stress that resulted in reduced plant development.


Assuntos
Arabidopsis/efeitos dos fármacos , Metaboloma , Proteoma , Timol/toxicidade , Ácido Abscísico , Arabidopsis/crescimento & desenvolvimento , Peróxido de Hidrogênio , Pressão Osmótica , Estresse Oxidativo , Fotossíntese , Folhas de Planta
5.
PLoS One ; 15(5): e0233503, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32442184

RESUMO

Recently-emerged base editing technologies could create single base mutations at precise genomic positions without generation DNA double strand breaks. Herbicide resistant mutations have been successfully introduced to different plant species, including Arabidopsis, watermelon, wheat, potato and tomato via C to T (or G to A on the complementary strand) base editors (CBE) at the P197 position of endogenous acetolactate synthase (ALS) genes. Additionally, G to A conversion to another conserved amino acid S653 on ALS gene could confer tolerance to imidazolinone herbicides. However, no such mutation was successfully generated via CBE, likely due to the target C base is outside of the classic base editing window. Since CBE driven by egg cell (EC) specific promoter would re-edit the wild type alleles in egg cells and early embryos, we hypothesized the diversity of base editing outcomes could be largely increased at later generations to allow selection of desired herbicide resistant mutants. To test this hypothesis, we aimed to introduce C to T conversion to the complement strand of S653 codon at ALS gene, hosting a C at the 10th position within the 20-nt spacer sequence outside of the classic base editing window. While we did not detect base-edited T1 plants, efficient and diverse base edits emerged at later generations. Herbicide resistant mutants with different editing outcomes were recovered when T3 and T4 seeds were subject to herbicide selection. As expected, most herbicide resistant plants contained S653N mutation as a result of G10 to A10. Our results showed that CBE could create imidazolinone herbicide resistant trait in Arabidopsis and be potentially applied to crops to facilitate weed control.


Assuntos
Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Resistência a Herbicidas/genética , Acetolactato Sintase/genética , Substituição de Aminoácidos , Proteínas de Arabidopsis/genética , Sequência de Bases , Sistemas CRISPR-Cas , DNA de Plantas/genética , Edição de Genes , Genes de Plantas , Herbicidas/farmacologia , Imidazolinas/farmacologia , Mutagênese Sítio-Dirigida , Melhoramento Vegetal , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Seleção Genética , Controle de Plantas Daninhas
6.
PLoS One ; 15(5): e0228515, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32407318

RESUMO

BACKGROUND: Recently, it was found that 1% Phytagel plates used to conduct Arabidopsis thaliana seedling phenotypic analysis no longer reproduced previously published results. This Phytagel, which is produced in China (Phytagel C), has replace American-made Phytagel (Phytagel), which is no longer commercially available. In this study, we present the impact of Phytagel produced in the United States vs. China on seedling phenotypic analysis. As a part of this study, an alternative gelling agent has been identified that is capable of reproducing previously published seedling morphometrics. RESULTS: Phytagel and Phytagel C were investigated based on their ability to reproduce the subtle phenotype of the sob3-4 esc-8 double mutant. Fluence-rate-response analysis of seedlings grown on 1% Phytagel C plates failed to replicate the sob3-4 esc-8 subtle phenotype seen on 1% Phytagel. Furthermore, root penetrance analysis showed a significant difference between sob3-4 esc-8 seedlings grown on 1% Phytagel and 1% Phytagel C. It was also found that 1% Phytagel C was significantly harder than 1% Phytagel. As a replacement for Phytagel C, Gellan was tested. 1% Gellan was able to reproduce the subtle phenotype of sob3-4 esc-8. Furthermore, there was no significant difference in root penetration of the wild type or sob3-4 esc-8 seedlings between 1% Phytagel and 1% Gellan. This may be due to the significant reduction in hardness in 1% Gellan plates compared to 1% Phytagel plates. Finally, we tested additional concentrations of Gellan and found that seedlings on 0.6% Gellan looked more uniform while also being able to reproduce previously published results. CONCLUSIONS: Phytagel has been the standard gelling agent for several studies involving the characterization of subtle seedling phenotypes. After production was moved to China, Phytagel C was no longer capable of reproducing these previously published results. An alternative gelling agent, Gellan, was able to reproduce previously published seedling phenotypes at both 1% and 0.6% concentrations. The information provided in this manuscript is beneficial to the scientific community as whole, specifically phenomics labs, as it details key problematic differences between gelling agents that should be performing identically (Phytagel and Phytagel C).


Assuntos
Arabidopsis/crescimento & desenvolvimento , Géis/farmacologia , Reprodução/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Fenômica , Fenótipo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Reprodução/genética , Plântula/efeitos dos fármacos , Plântula/genética
7.
PLoS Genet ; 16(5): e1008797, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32392219

RESUMO

Sun-loving plants perceive the proximity of potential light-competing neighboring plants as a reduction in the red:far-red ratio (R:FR), which elicits a suite of responses called the "shade avoidance syndrome" (SAS). Changes in R:FR are primarily perceived by phytochrome B (phyB), whereas UV-B perceived by UV RESISTANCE LOCUS 8 (UVR8) elicits opposing responses to provide a counterbalance to SAS, including reduced shade-induced hypocotyl and petiole elongation. Here we show at the genome-wide level that UVR8 broadly suppresses shade-induced gene expression. A subset of this gene regulation is dependent on the UVR8-stabilized atypical bHLH transcription regulator LONG HYPOCOTYL IN FAR-RED 1 (HFR1), which functions in part redundantly with PHYTOCHROME INTERACTING FACTOR 3-LIKE 1 (PIL1). In parallel, UVR8 signaling decreases protein levels of the key positive regulators of SAS, namely the bHLH transcription factors PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5, in a COP1-dependent but HFR1-independent manner. We propose that UV-B antagonizes SAS via two mechanisms: degradation of PIF4 and PIF5, and HFR1- and PIL1-mediated inhibition of PIF4 and PIF5 function. This work highlights the importance of typical and atypical bHLH transcription regulators for the integration of light signals from different photoreceptors and provides further mechanistic insight into the crosstalk of UVR8 signaling and SAS.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/química , Proteínas Cromossômicas não Histona/genética , Proteínas de Ligação a DNA/química , Raios Ultravioleta/efeitos adversos , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Regulação para Baixo , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Estabilidade Proteica , Proteólise , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo
8.
Ecotoxicol Environ Saf ; 199: 110727, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32446101

RESUMO

Sulfonamides (SAs) are antibiotics widely used in clinical practice, livestock and poultry production, and the aquaculture industry. The compounds enter the soil environment largely through livestock and poultry manure application to farmland. SAs not only affect plant growth, but also pose a potential threat to human health through SA residues in plant tissues. In particular, sulfamethoxazole (SMZ) has been classified as a Category 3 carcinogen by the World Health Organization, and thus its soil ecological toxicity and possible health risks are of concern. Using A. thaliana as a model plant, stress responses and biological residues of sulfadiazine (SD), sulfametoxydiazine (SMD), and SMZ were investigated in the present study. Root length and aboveground plant biomass were significantly inhibited by the three types of SA, whereas lateral roots exposed to SMD grew vigorously. The contents of chlorophyll a and chlorophyll b and photosystem II maximum photochemical quantum yield declined with increase in drug concentration, which indicated that exposure to SAs affected photosynthesis and inhibited chlorophyll synthesis in A. thaliana. With increase in drug concentration, reactive oxygen species (ROS) accumulation in the leaves increased significantly. Activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were activated at low SA concentrations, but increased lipid peroxidation occurred with increase in SA concentration. Of the three compounds, SMZ was the most toxic to A. thaliana, followed by SD, and SMD was the least toxic. The results indicated that the risk of SMD entering an organism through the food chain is greater than that for SMZ and SD.


Assuntos
Antibacterianos/toxicidade , Arabidopsis/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Poluentes do Solo/toxicidade , Sulfanilamidas/toxicidade , Antioxidantes/metabolismo , Arabidopsis/enzimologia , Arabidopsis/crescimento & desenvolvimento , Clorofila/metabolismo , Clorofila A/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo
9.
Artigo em Inglês | MEDLINE | ID: mdl-32278957

RESUMO

Norharmane is an indole alkaloid that can be found in several terrestrial plants, as well as in some dinoflagellates and cyanobacteria. The aim of this study was to focus on the way this metabolite impacts the plant metabolism of the model species Arabidopsis thaliana. This metabolite caused increase of secondary and adventitious roots, as well as torsion, toxic effects, and a decrease in root length. Moreover, norharmane altered the cellular arrangement, resulting in unfinished cell walls, decreased auxin content and inhibited PIN proteins activity. All the alterations suggest that norharmane alters polar auxin transport by inhibiting PIN2, PIN3 and PIN7 transport proteins, thus causing a significant inhibitory effect on the growth of A. thaliana seedlings.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Carbolinas , Regulação da Expressão Gênica de Plantas , Raízes de Plantas , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Transporte Biológico/efeitos dos fármacos , Carbolinas/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos
10.
Int J Mol Sci ; 21(7)2020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-32218176

RESUMO

MiPEPs are short natural peptides encoded by microRNAs in plants. Exogenous application of miPEPs increases the expression of their corresponding miRNA and, consequently, induces consistent phenotypical changes. Therefore, miPEPs carry huge potential in agronomy as gene regulators that do not require genome manipulation. However, to this end, it is necessary to know their mode of action, including where they act and how they enter the plants. Here, after analyzing the effect of Arabidopsis thaliana miPEP165a on root and aerial part development, we followed the internalization of fluorescent-labelled miPEP165a into roots and compared its uptake into endocytosis-altered mutants to that observed in wild-type plants treated or not with endocytosis inhibitors. The results show that entry of miPEP165a involves both a passive diffusion at the root apex and endocytosis-associated internalization in the differentiation and mature zones. Moreover, miPEP165a is unable to enter the central cylinder and does not migrate from the roots to the aerial part of the plant, suggesting that miPEPs have no systemic effect.


Assuntos
Arabidopsis/efeitos dos fármacos , Endocitose , Arabidopsis/citologia , Arabidopsis/metabolismo , Transporte Biológico , Divisão Celular/efeitos dos fármacos , Difusão , Endocitose/efeitos dos fármacos , Fenótipo , Raízes de Plantas/citologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas
11.
Artigo em Inglês | MEDLINE | ID: mdl-32120172

RESUMO

Chitosan oligosaccharides (COS) worked effectively in multiple plant-pathogen interactions as plant immunity regulator, however, due to the complexity of the COS-induced immune signaling network, the topic requires further investigation. In the present study, quantitative analysis of proteins was performed to investigate the underlying mechanism of COS induced resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) in Arabidopsis thaliana. 4303 proteins were successfully quantified, 186, 217 and 207 proteins were differently regulated in mock + Pst, COS, and COS + Pst treated plants, respectively, compared with mock plants. From detailed functional and hierarchical clustering analysis, a priming effect of COS on plant immune system by pre-regulated the key proteins related to signaling transduction, defense response, cell wall biosynthesis and modification, plant growth and development, gene transcription and translation, which confers enhanced resistance when Pst DC3000 infection in Arabidopsis. Moreover, RACK1B which has the potential to be the key kinase receptor for COS signals was found out by protein-protein interaction network analysis of COS responsive proteins. In conclusion, COS treatment enable plant to fine-tuning its defense mechanisms for a more rapid and stronger response to future pathogen attacks, which obviously enhances plants defensive capacity that makes COS worked effectively in multiple plant-pathogen interactions.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Quitosana , Resistência à Doença , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Quitosana/farmacologia , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Proteômica , Pseudomonas syringae/fisiologia
12.
Artigo em Inglês | MEDLINE | ID: mdl-32135477

RESUMO

Although WRKY transcription factors (TFs) are known to be involved in the regulation of plant root development, the mechanisms by which these TFs regulate plant tolerance to ammonium (NH4+) toxicity remain unclear. To identify the molecular mechanisms underlying NH4+-induced repression of primary root growth and NH4+ sensitivity in Arabidopsis, wild-type (Col-0) and mutant (wrky23) plants were treated with 10 mM KNO3 (control) or 5 mM (NH4)2SO4 (NH4+ toxicity) for 7 days. Under NH4+ toxicity, the fresh weight of wrky23 mutant was significantly lower than that of Col-0 plants, and the NH4+ concentration in wrky23 roots was significantly higher than that in Col-0 roots. However, we observed no significant differences between the two genotypes under the control treatment. Ammonium transporter AMT1;2 expression was induced in wrky23 roots but not in Col-0 roots. The transcript levels of cytosolic glutamine synthetase-encoding genes and activity of glutamine synthetase did not differ significantly between wrky23 and Col-0. Furthermore, the fluorescence and staining patterns of DR5::GFP and DR5::GUS, respectively, were more pronounced under NH4+ toxicity than under the control treatment. Collectively, our results indicate that AMT1;2 expression was induced in the wrky23 mutant in response to NH4+ toxicity, leading to NH4+ accumulation in the roots and primary root growth repression. Under NH4+ toxicity, both auxin transport and distribution were affected, and auxin accumulation in the root tips inhibited primary root growth in the wrky23 mutant. Our study provides important insights into the molecular mechanisms by which WRKY23 TF regulates plant responses to NH4+ toxicity.


Assuntos
Compostos de Amônio , Proteínas de Arabidopsis , Arabidopsis , Compostos de Amônio/toxicidade , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ácidos Indolacéticos/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Fatores de Transcrição/metabolismo
13.
Artigo em Inglês | MEDLINE | ID: mdl-32155448

RESUMO

Nitric oxide (NO) and potassium (K+) exert a profound influence on the acclimation of plants to multiple stress conditions. A recent report indicated that exogenous addition of an NO donor causes, under conditions of adequate K+ supply, a detrimental effect on K+ status. It remains unknown whether an exogenous NO source could negatively affect the potential capture of this element when plants are faced with a K+ shortage. In this work we offer evidence that, under conditions of K+-deprivation, the addition of the naturally occurring NO donor, S-nitrosoglutathione (GSNO), diminishes the potential inward transport of the K+-analogue rubidium (Rb+) from diluted Rb+ concentrations in Arabidopsis thaliana. Studies with the akt1-2 mutant, lacking the AKT1 inward-rectifier K+-channel involved in K+-uptake, unveiled that the effect of GSNO on Rb+-influx involves a non-AKT1 component. In addition, exposure to the NO-donor led to down-regulation of transcripts coding for the AtHAK5 K+-transporter, a major component of the K+-transport machinery in K+-deprived plants. Moreover, studies with the hak5 mutant showed that GSNO could either stimulate Rb+-uptake or does not lead to a significant effect on Rb+-uptake relative to -K+ and to -K+ in the presence of decayed GSNO, respectively, thus indicating that the presence of AtHAK5 is required for GSNO exerting an inhibitory effect.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Rubídio , S-Nitrosoglutationa , Arabidopsis/efeitos dos fármacos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Doadores de Óxido Nítrico/farmacologia , Potássio/metabolismo , Rubídio/metabolismo , S-Nitrosoglutationa/farmacologia
14.
Proc Natl Acad Sci U S A ; 117(12): 6910-6917, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32152121

RESUMO

Auxin is a class of plant hormone that plays a crucial role in the life cycle of plants, particularly in the growth response of plants to ever-changing environments. Since the auxin responses are concentration-dependent and higher auxin concentrations might often be inhibitory, the optimal endogenous auxin level must be closely controlled. However, the underlying mechanism governing auxin homeostasis remains largely unknown. In this study, a UDP-glycosyltransferase (UGT76F1) was identified from Arabidopsis thaliana, which participates in the regulation of auxin homeostasis by glucosylation of indole-3-pyruvic acid (IPyA), a major precursor of the auxin indole-3-acetic acid (IAA) biosynthesis, in the formation of IPyA glucose conjugates (IPyA-Glc). In addition, UGT76F1 was found to mediate hypocotyl growth by modulating active auxin levels in a light- and temperature-dependent manner. Moreover, the transcription of UGT76F1 was demonstrated to be directly and negatively regulated by PIF4, which is a key integrator of both light and temperature signaling pathways. This study sheds a light on the trade-off between IAA biosynthesis and IPyA-Glc formation in controlling auxin levels and reveals a regulatory mechanism for plant growth adaptation to environmental changes through glucosylation of IPyA.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Glucose/metabolismo , Hipocótilo/crescimento & desenvolvimento , Ácidos Indolacéticos/farmacologia , Indóis/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/metabolismo , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Depuradores de Radicais Livres/química , Depuradores de Radicais Livres/metabolismo , Glucosiltransferases/metabolismo , Glicosilação , Hipocótilo/efeitos dos fármacos , Hipocótilo/metabolismo , Hipocótilo/efeitos da radiação , Indóis/química , Luz , Reguladores de Crescimento de Planta/farmacologia , Plântula , Temperatura
15.
Nat Commun ; 11(1): 1264, 2020 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-32152287

RESUMO

Wildfires can encourage the establishment of invasive plants by releasing potent germination stimulants, such as karrikins. Seed germination of Brassica tournefortii, a noxious weed of Mediterranean climates, is strongly stimulated by KAR1, the archetypal karrikin produced from burning vegetation. In contrast, the closely-related yet non-fire-associated ephemeral Arabidopsis thaliana is unusual because it responds preferentially to KAR2. The α/ß-hydrolase KARRIKIN INSENSITIVE 2 (KAI2) is the putative karrikin receptor identified in Arabidopsis. Here we show that B. tournefortii expresses three KAI2 homologues, and the most highly-expressed homologue is sufficient to confer enhanced responses to KAR1 relative to KAR2 when expressed in Arabidopsis. We identify two amino acid residues near the KAI2 active site that explain the ligand selectivity, and show that this combination has arisen independently multiple times within dicots. Our results suggest that duplication and diversification of KAI2 proteins could confer differential responses to chemical cues produced by environmental disturbance, including fire.


Assuntos
Arabidopsis/metabolismo , Brassica/metabolismo , Proteínas de Transporte/efeitos dos fármacos , Proteínas de Transporte/metabolismo , Furanos/farmacologia , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/metabolismo , Piranos/farmacologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis , Brassica/efeitos dos fármacos , Brassica/genética , Domínio Catalítico , Fogo , Regulação da Expressão Gênica de Plantas , Germinação/efeitos dos fármacos , Germinação/fisiologia , Hidrolases/genética , Hidrolases/metabolismo , Magnoliopsida , Proteínas de Plantas/efeitos dos fármacos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plântula , Sementes/efeitos dos fármacos , Sementes/fisiologia , Análise de Sequência de Proteína , Transcriptoma , Incêndios Florestais
16.
Ecotoxicol Environ Saf ; 192: 110252, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32014725

RESUMO

Glutaredoxins (Grxs) are small multifunctional redox proteins. Grxs have glutathione-dependent oxidoreductase activity in the presence of glutathione reductase and NADPH. The role of Grxs is well studied in heavy metal tolerance in prokaryotic and mammalian systems but not in plant genera. In the present study, a chickpea glutaredoxin (CaGrx) gene (LOC101493651) has been investigated against metal stress based on its primary screening in chickpea which revealed higher up-regulation of CaGrx gene under various heavy metals (AsIII-25 µM, AsV-250 µM, Cr(VI)-300 µM, and Cd-500 µM) stress. This CaGrx gene was overexpressed in Arabidopsis thaliana and investigated various biochemical and physiological performances under each metal stress. Transgenic plants showed significant up-regulation of the CaGrx gene during qRT-PCR analysis as well as longer roots, higher seed germination, and survival efficiency during each metal stress. The levels of stress markers, TBARS, H2O2, and electrolyte leakage were found to be less in transgenic lines as compared to WT revealed less toxicity in transgenics. The total accumulation of AsIII, AsV, and Cr(VI) were significantly reduced in all transgenic lines except Cd, which was slightly reduced. The physiological parameters such as net photosynthetic rate (PN), stomatal conductance (gs), transpiration (E), water use efficiency (WUE), photochemical quenching (qP), and electron transport rate (ETR), were maintained in transgenic lines during metal stress. Various antioxidant enzymes such as glutaredoxin (GRX), glutathione reductase (GR), glutathione peroxidase (GPX), glutathione-S-transferase (GST), ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), antioxidant molecules (ascorbate, GSH) and stress-responsive amino acids (proline and cysteine) levels were significantly increased in transgenic lines which provide metal tolerance. The outcome of this study strongly indicates that the CaGrx gene participates in the moderation of metal stress in Arabidopsis, which can be utilized in biotechnological interventions to overcome heavy metal stress conditions in different crops.


Assuntos
Antioxidantes/metabolismo , Cicer/enzimologia , Glutarredoxinas/metabolismo , Metais Pesados/toxicidade , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Ascorbato Peroxidases/metabolismo , Catalase/metabolismo , Glutarredoxinas/genética , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Estresse Oxidativo , Oxirredutases/metabolismo , Superóxido Dismutase/metabolismo
17.
Ecotoxicol Environ Saf ; 193: 110302, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32087445

RESUMO

Based on previous studies and preliminary test results, 200 µM was used as the test concentration of chromium (Cr), and changes in the gene expression profile of Arabidopsis thaliana in response to 24-h treatments of Cr(III) and Cr(VI) were analyzed using the Arabidopsis ATH1 Genome Array. The results were as follows. There were 238 upregulated genes and 858 downregulated genes in response to treatments with Cr(III) and Cr(VI). For Cr(III) and Cr(VI) treatments, there were 185 and 587 specifically upregulated genes as well as 220 and 956 specifically downregulated genes, respectively. Among the common differentially expressed genes (DEGs), the expression levels of genes involved in redox, secondary metabolism, and energy metabolism processes were significantly downregulated, while those of genes related to the stress response, photosynthesis, and sulfur metabolism were significantly upregulated. These findings indicated that Cr seriously affected the normal activities of A. thaliana cells. Some genes associated with stress and regulation were upregulated to adapt to the stress caused by Cr. Among the unique DEGs, the expression levels of genes involved in indole-3-acetic acid (IAA) regulatory pathway were significantly increased in response to Cr(III) treatment; the expression levels of genes involved in the abscisic acid (ABA) regulation pathway and carotenoid synthesis were significantly increased following Cr(VI) treatment. These results revealed some differences in response to Cr(III) and Cr(VI) in A. thaliana.


Assuntos
Arabidopsis/efeitos dos fármacos , Cromatos/toxicidade , Compostos de Cromo/toxicidade , Nitratos/toxicidade , Compostos de Potássio/toxicidade , Transcriptoma/efeitos dos fármacos , Ácido Abscísico/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Metabolismo Energético/efeitos dos fármacos , Metabolismo Energético/genética , Ácidos Indolacéticos/metabolismo , Análise em Microsséries , Oxirredução , Fotossíntese/efeitos dos fármacos , Fotossíntese/genética
18.
Artigo em Inglês | MEDLINE | ID: mdl-32005390

RESUMO

Root-derived abscisic acid (ABA) is known to regulate shoot physiology, such as stomata closure. Conversely, the basipetal regulatory effect of shoot-derived ABA is poorly understood. Herein, we report that simulation of shoot-ABA accumulation by exogenous application of ABA to shoots basipetally stimulates primary root (PR) growth. ABA applied to shoots accelerates root cell division, as evidenced by the increase in meristem size and cell number and the intensity of CYCB1;1::GFP (a mitosis marker). Root ABA content was not changed following shoot ABA application, although the ABA reporter line RAB18::GFP showed an increase in ABA in the cotyledons. Shoot-ABA application increases basipetal auxin transport by 114 %. Shoot-ABA-promoted PR growth can be abolished by attenuating basipetal auxin flux using 2,3,5-triiodobenzoic acid (TIBA, an auxin transport inhibitor), demonstrating that ABA promotes PR growth by increasing basipetal auxin transport. Root cell elongation, evaluated by the total length of the first 7 cells in the elongation zone (EZ), was increased by 56 % following shoot-ABA application. The cell walls of the root EZ were alkalinized by ABA, as exhibited by 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt staining. Higher pH promotes both PR growth and cell elongation. Thus, shoot-ABA promotes cell elongation by alkalinizing the cell wall. In light of our results, we provide a representative detailed model of the basipetal regulatory effect of ABA on PR growth.


Assuntos
Ácido Abscísico/farmacologia , Arabidopsis/fisiologia , Reguladores de Crescimento de Planta/farmacologia , Raízes de Plantas/fisiologia , Transdução de Sinais , Ácido Abscísico/administração & dosagem , Arabidopsis/efeitos dos fármacos , Transporte Biológico , Divisão Celular/efeitos dos fármacos , Meristema/efeitos dos fármacos , Meristema/fisiologia , Raízes de Plantas/efeitos dos fármacos , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/metabolismo
19.
Artigo em Inglês | MEDLINE | ID: mdl-32065921

RESUMO

Nitrated fatty acids (NO2-FAs) are important signaling molecules in mammals. NO2-FAs are formed by the addition reaction of nitric oxide- and nitrite-derived nitrogen dioxide with unsaturated fatty acid double bonds. The study of NO2-FAs in plant systems constitutes an interesting and emerging area. The presence of NO2-FA has been reported in olives, peas, rice and Arabidopsis. To gain a better understanding of the role of NO2-FA on plant physiology, we analyzed the effects of exogenous application of nitro-oleic acid (NO2-OA). In tomato cell suspensions we found that NO2-OA induced reactive oxygen species (ROS) production in a dose-dependent manner via activation of NADPH oxidases, a mechanism that requires calcium entry from the extracellular compartment and protein kinase activation. In tomato and Arabidopsis leaves, NO2-OA treatments induced two waves of ROS production, resembling plant defense responses. Arabidopsis NADPH oxidase mutants showed that NADPH isoform D (RBOHD) was required for NO2-OA-induced ROS production. In addition, on Arabidopsis isolated epidermis, NO2-OA induced stomatal closure via RBOHD and F. Altogether, these results indicate that NO2-OA triggers NADPH oxidase activation revealing a new signaling role in plants.


Assuntos
Arabidopsis/metabolismo , Lycopersicon esculentum/metabolismo , NADPH Oxidases/metabolismo , Ácido Oleico/farmacologia , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/metabolismo , Células Cultivadas , Lycopersicon esculentum/efeitos dos fármacos , Imunidade Vegetal/efeitos dos fármacos , Imunidade Vegetal/imunologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/fisiologia
20.
Artigo em Inglês | MEDLINE | ID: mdl-32097848

RESUMO

Ethylene response factors (ERFs) are involved in the regulation of plant responses to biotic and abiotic stresses. Here we provide evidence for a role of ERF96, a member of the ERF transcription factor group IX, in selenite tolerance in Arabidopsis. ERF96 gene was rapidly up-regulated in response to selenite stress. Overexpression of ERF96 enhanced Arabidopsis resistance to selenite stress, while ERF96-silenced plants demonstrated wild-type (WT) resistance to selenite. In addition, the overexpression plants had significantly lower selenium (Se) content in shoots when subjected to selenite stress. Further investigation indicated that overexpression of ERF96 reduced transcript levels of selenite/phosphate transporters PHT1;1 and PHT2;1, which influenced Arabidopsis Se uptake and allocation in the presence of selenite. Moreover, our experiments showed that overexpression of ERF96 enhanced Arabidopsis antioxidant activity. Under selenite stress, ERF96-overexpressing lines exhibited the significant increases in catalase (CAT) and glutathione peroxidase (GPX) activities as well as the glutathione (GSH) content, while had a decrease in reactive oxygen species (ROS) accumulation compared to WT. Taken together, our results demonstrate that ERF96 plays a positive role in the regulation of selenite tolerance in Arabidopsis.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Selênio , Estresse Fisiológico , Fatores de Transcrição , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Expressão Gênica , Plantas Geneticamente Modificadas , Selênio/toxicidade , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
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